The hydraulic oil tank that stores oil to be delivered to oil hydraulic equipment is mounted on a working machine including the oil hydraulic equipment such as an oil hydraulic pump. The hydraulic oil tank is a container including a delivery pipe and an inflow pipe. The oil stored in the hydraulic oil tank is delivered to the oil hydraulic equipment through the delivery pipe. On the other hand, oil discharged from the oil hydraulic equipment is returned to the inside of the hydraulic oil tank through the inflow pipe.
Foreign objects such as chip powder and bubbles (air) may be mixed in the oil returned to the hydraulic oil tank. Further, foreign objects may be mixed inside the hydraulic oil tank. When the oil in which the foreign objects and the bubbles are still mixed is delivered from the hydraulic oil tank, the oil significantly affects the service life of the oil hydraulic equipment.
Therefore, in this type of hydraulic oil tank, normally, a filter device and/or a strainer device are provided to the inflow pipe and the delivery pipe, and a baffle plate is provided between the inflow pipe and the delivery pipe. Specifically, foreign objects are removed from the oil returned to the hydraulic oil tank by providing the filter device to the inflow pipe, and filtered oil is delivered to the oil hydraulic equipment by providing the strainer device to the delivery pipe. The baffle plate facilitates removing bubbles in the oil by diverting a route of the oil from the inflow pipe to the delivery pipe and prevents a case where oil containing bubbles is delivered to the oil hydraulic equipment (for example, see Patent Literature 1 and Patent Literature 2).